"If, then, Mortimer Tregennis disappeared from the scene, and yet some outside person affected the card-players, how can we reconstruct that person, and how was such an impression of horror conveyed? Mrs. Porter may be eliminated. She is evidently harmless. Is there any evidence that someone crept up to the garden window and in some manner produced so terrific an effect that he drove those who saw it out of their senses? The only suggestion in this direction comes from Mortimer Tregennis himself, who says that his brother spoke about some movement in the garden. That is certainly remarkable, as the night was rainy, cloudy, and dark. Anyone who had the design to alarm these people would be compelled to place his very face against the glass before he could be seen. There is a three-foot flower-border outside this window, but no indication of a footmark. It is difficult to imagine, then, how an outsider could have made so terrible an impression upon the company, nor have we found any possible motive for so strange and elaborate an attempt. You perceive our difficulties, Watson?" "They are only too clear," I answered with conviction. "And yet, with a little more material, we may prove that they are not insurmountable," said Holmes. "I fancy that among your extensive archives, Watson, you may find some which were nearly as obscure. Meanwhile, we shall put the case aside until more accurate data are available, and devote the rest of our morning to the pursuit of neolithic man." I may have commented upon my friend's power of mental detachment, but never have I wondered at it more than upon that spring morning in Cornwall when for two hours he discoursed upon celts, arrowheads, and shards, as lightly as if no sinister mystery were waiting for his solution. It was not until we had returned in the afternoon to our cottage that we found a visitor awaiting us, who soon brought our minds back to the matter in hand. Neither of us needed to be told who that visitor was. The huge body, the craggy and deeply seamed face with the fierce eyes and hawk-like nose, the grizzled hair which nearly brushed our cottage ceiling, the beard--golden at the fringes and white near the lips, save for the nicotine stain from his perpetual cigar--all these were as well known in London as in Africa, and could only be associated with the tremendous personality of Dr. Leon Sterndale, the great lion-hunter and explorer.